Transgenic plants against malaria

Since the ancient times, mankind has used plants to treat diseases. An example is the plant Artemisia annua, used for over 2,000 years in traditional Chinese medicine to treat intermittent fevers. Nowadays, the artemisinin molecule - the active ingredient synthesized in the microscopic hairs (trichomes) of this plant - is the main component of malaria treatments worldwide. In fact, the Chinese scientist Youyou Tu was awarded in 2015 with the Nobel Prize in Medicine for the discovery of artemisinin and its application in therapies against malaria.

Regardless of artemisinin's effectiveness against malaria and other diseases caused by parasites and despite its anti-tumor potential, its usage faces a problem: the low content produced by the plant and the high cost of its chemical synthesis result in a scarce and expensive drug.

Now, an international research team has been able to obtain, through genetic engineering, Artemisia annua plants that produce twice as much artemisinin. The work, published in The Plant Journal, identifies a gene involved in the formation of plant trichomes and in the synthesis of terpenes, such as artemisinin. "We have discovered that the AaMYB1 gene has a dual function: it promotes trichome formation in the leaves and artemisinin synthesis inside the trichomes", explains senior author of the article. "By manipulating this gene, we have managed to grow plants which contain much more artemisinin than their wild-type counterparts," senior author adds.

The scientists were able to identify the gene AaMYB1 among the array of genes expressed in Artemisia trichomes. At CRAG, the researchers designed transgenic plants that overexpressed this gene and found that they accumulated larger doses of artemisinin than non-genetically modified plants.

But the investigation went further. To confirm the role of the AaMYB1 gene in the formation of plant trichomes, the researchers searched for similar genes in the model plant Arabidopsis thaliana and found the gene AtMYB61. When this gene was overexpressed in the model plant, it also produced a higher amount of trichomes on its leaves, demonstrating that these genes play a key role in the formation of trichomes in evolutionarily distant species.